While running for a bus in Sheffield, I slipped and broke my wrist. Unsurprisingly I let out a 4-letter word, as I landed in a heap among a group of shoppers. Climbing to my feet, I asked them to 'Excuse my French'.
The following day, one of my pupils said to me "Sir, my Mum says she will excuse your French!".
There are half a million people in Sheffield, so why was it that, when I swore for the first time in several years, I had to do it in front of a parent who'd entrusted me to teach her son some decent manners? ;-)